Bottom Line:
Absence epilepsy (AE) is etiologically heterogeneous and has at times been associated with idiopathic dystonia.We compared the blink reflex recovery cycle in children belonging to all four subgroups.In children with AE, dysgraphia is highly prevalent and has a homogeneous, distinctive pathophysiological substrate consistent with idiopathic dystonia.

Background: Absence epilepsy (AE) is etiologically heterogeneous and has at times been associated with idiopathic dystonia.

Objectives: Based on the clinical observation that children with AE often exhibit, interictally, a disorder resembling writer's cramp but fully definable as dysgraphia, we tested the hypothesis that in this particular population dysgraphia would represent a subtle expression of dystonia.

Methods: We ascertained the prevalence of dysgraphia in 82 children with AE (mean age 9.7) and average intelligence and compared them with 89 age-, gender- and class-matched healthy children (mean age 10.57) using tests for handwriting fluency and quality, based on which we divided patients and controls into four subgroups: AE/dysgraphia, AE without dysgraphia, controls with dysgraphia and healthy controls. We compared the blink reflex recovery cycle in children belonging to all four subgroups.

Results: We identified dysgraphia in 17/82 children with AE and in 7/89 controls (20.7 vs 7.8%; P = 0.016) with the former having a 3.4-times higher risk of dysgraphia regardless of age and gender (odd ratio: 3.49; 95% CI 1.2, 8.8%). The AE/dysgraphia subgroup performed worse than controls with dysgraphia in one test of handwriting fluency (P = 0.037) and in most trials testing handwriting quality (P< 0.02). In children with AE/dysgraphia the blink reflex showed no suppression at short interstimulus intervals, with a difference for each value emerging when comparing the study group with the three remaining subgroups (P<0.001).

Conclusions: In children with AE, dysgraphia is highly prevalent and has a homogeneous, distinctive pathophysiological substrate consistent with idiopathic dystonia.

pone.0130883.g002: Handwriting performance.(A) Patient 12. Example of handwriting during “uno “(above) and “le” (below) test. The child performed slowly. (B) Patient 9. Example of handwriting performance during ‘best’ (above) and ‘faster’ (below) conditions. We considered this patient’s performance as inadequate.

Mentions:
Using the study battery illustrated in the ‘Methods’ section, we identified dysgraphia in 17/82 children with absence epilepsy and in 7/89 controls (20.7 vs 7.8%; a difference of 12.9%, 95% CI 2.5, 23.3%; P = 0.016) (an example of handwriting of children with absence epilepsy/dysgraphia is illustrated in Fig 2). Children with absence epilepsy had a 3.4-times higher risk of having dysgraphia than controls, regardless of age and gender (OR: 3.49; 95% CI 1.2, 8.8%). The average age of children with absence epilepsy/dysgraphia at the time of the study was 9.6 years (SD 1.6; 52.9% males). The average age at onset of absence seizures was 6.28 years (SD 2.5). Thirteen patients were seizure-free on medication at the time of the study while the remaining four still manifested sporadic absence seizures. Cognitive level was average in all patients and IQ testing was performed in 10/17 patients. The five patients re-tested after 5 years remained seizure free during the follow-up period. Clinical data are summarized in Table 1.

pone.0130883.g002: Handwriting performance.(A) Patient 12. Example of handwriting during “uno “(above) and “le” (below) test. The child performed slowly. (B) Patient 9. Example of handwriting performance during ‘best’ (above) and ‘faster’ (below) conditions. We considered this patient’s performance as inadequate.

Mentions:
Using the study battery illustrated in the ‘Methods’ section, we identified dysgraphia in 17/82 children with absence epilepsy and in 7/89 controls (20.7 vs 7.8%; a difference of 12.9%, 95% CI 2.5, 23.3%; P = 0.016) (an example of handwriting of children with absence epilepsy/dysgraphia is illustrated in Fig 2). Children with absence epilepsy had a 3.4-times higher risk of having dysgraphia than controls, regardless of age and gender (OR: 3.49; 95% CI 1.2, 8.8%). The average age of children with absence epilepsy/dysgraphia at the time of the study was 9.6 years (SD 1.6; 52.9% males). The average age at onset of absence seizures was 6.28 years (SD 2.5). Thirteen patients were seizure-free on medication at the time of the study while the remaining four still manifested sporadic absence seizures. Cognitive level was average in all patients and IQ testing was performed in 10/17 patients. The five patients re-tested after 5 years remained seizure free during the follow-up period. Clinical data are summarized in Table 1.

Bottom Line:
Absence epilepsy (AE) is etiologically heterogeneous and has at times been associated with idiopathic dystonia.We compared the blink reflex recovery cycle in children belonging to all four subgroups.In children with AE, dysgraphia is highly prevalent and has a homogeneous, distinctive pathophysiological substrate consistent with idiopathic dystonia.

Background: Absence epilepsy (AE) is etiologically heterogeneous and has at times been associated with idiopathic dystonia.

Objectives: Based on the clinical observation that children with AE often exhibit, interictally, a disorder resembling writer's cramp but fully definable as dysgraphia, we tested the hypothesis that in this particular population dysgraphia would represent a subtle expression of dystonia.

Methods: We ascertained the prevalence of dysgraphia in 82 children with AE (mean age 9.7) and average intelligence and compared them with 89 age-, gender- and class-matched healthy children (mean age 10.57) using tests for handwriting fluency and quality, based on which we divided patients and controls into four subgroups: AE/dysgraphia, AE without dysgraphia, controls with dysgraphia and healthy controls. We compared the blink reflex recovery cycle in children belonging to all four subgroups.

Results: We identified dysgraphia in 17/82 children with AE and in 7/89 controls (20.7 vs 7.8%; P = 0.016) with the former having a 3.4-times higher risk of dysgraphia regardless of age and gender (odd ratio: 3.49; 95% CI 1.2, 8.8%). The AE/dysgraphia subgroup performed worse than controls with dysgraphia in one test of handwriting fluency (P = 0.037) and in most trials testing handwriting quality (P< 0.02). In children with AE/dysgraphia the blink reflex showed no suppression at short interstimulus intervals, with a difference for each value emerging when comparing the study group with the three remaining subgroups (P<0.001).

Conclusions: In children with AE, dysgraphia is highly prevalent and has a homogeneous, distinctive pathophysiological substrate consistent with idiopathic dystonia.